Ocean Optics SpectraSuite - Manual (Page 145)

A: Experiment Tutorials
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A reference spectrum is taken when the light source is on and the there is no sample present. Click the
Store Reference Spectrum icon ( ) to take a reference spectrum.
A dark spectrum is taken in the absence of light. Block the light path, uncheck the Strobe/Lamp Enable
option on SpectraSuite’s Acquisition toolbar, or turn off the lamp, and then click the Store Dark Spectrum
icon (
) to take a dark spectrum.
Absorbance Experiments
Absorbance spectra are a measure of how much light a sample absorbs. For most samples, absorbance
relates linearly to the concentration of the substance. SpectraSuite calculates absorbance (A

) using the
following equation.
Where:
S

= Sample intensity at wavelength 
D

= Dark intensity at wavelength 
R

= Reference intensity at wavelength 
Typical absorbance setup: The light source (far right) sends light via an input fiber into a cuvette in a
cuvette holder (bottom center). The light interacts with the sample. The output fiber carries light from the
sample to the spectrometer (top center) connected to the computer (far left).
Absorbance is also proportional to the concentration of the substance interacting with the light (this is
known as Beer’s Law). Common absorption applications include the quantification of chemical
concentrations in aqueous or gaseous samples.